Variable stroke ejector mechanism

ABSTRACT

A die press ejector mechanism comprising a reciprocable ejector member, which engages a workpiece to eject the same from a die. The ejector member is engageable by one arm of a first oscillating bell crank, the other arm of which has a roller that is adjustable toward and away from the pivot axis of the bell crank. The roller is contacted by a plane surface which moves in a direction generally perpendicular to the line of adjustment travel of the roller. Preferably, the planar surface is provided on one arm of a second bell crank lever, the other arm of which is engaged by an actuating cam. As the second bell crank is oscillated by the cam, the planar surface pushes against the roller, causing the first bell crank to oscillate. The angular movement of the first bell crank depends upon the adjusted distance of the roller from the bell crank pivot axis.

United States Patent [191 Koch et a1.

[ June 28, 1974 [54] VARIABLE STROKE EIECTOR MECHANISM [75] Inventors: Friedrich-Karl Koch, Krefeld; Oskar Rahn, Kempen, both of Germany [73] Assignee: Peltzer & Ehlers, Krefeld, Germany [22] Filed: Aug. 18, 1972 211 Appl. No.: 281,996

[30] Foreign Application Priority Data Sept. 29, 1971 Germany 2148528 [56] References Cited UNITED STATES PATENTS 4/1951 Broscomb 10/11 E 11/1964 Carlson 10/11 Primary Examiner-Charles W. Lanham 1 Assistant Examiner-Robert M. Rogers Attorney, Agent, or Firm-Herbert E. Kidder [57] ABSTRACT A die press ejector mechanism comprising a reciprocable ejector member, which engages a workpiece to eject the same from a die. The ejector member is engageable by one arm of a first oscillating bell crank, the other arm of which has a roller that is adjustable toward and away from the pivot axis of the bell crank. The roller is contacted by a plane surface which moves in a directiongenerally perpendicular to the line of adjustment travel of the roller. Preferably, the planar surface is provided on one arm of a second bell crank lever, the other arm of which is engaged by an actuating cam. As the second bell crank is oscillated by the cam, the planar surface pushes against the roller, causing the first bell crank to oscillate. The angular movement of the first bell crank depends upon the adjusted distance of the roller from the bell crank pivot axis.

7 Claims, 2 Drawing Figures VARIABLE STROKE EJECTOR MECHANISM BACKGROUND OF THE INVENTION The invention relates to an ejector mechanism. The mechanism may be used for ejecting pressings from fixed dies of single-operation, double-operation or multistage presses, which have a control shaft carrying at least one cam acting through a double-arm rocking lever on an associated ejector bar.

An ejector mechanism for a die is disclosed in German Patent specification No. 1,059,268. Pressings ejected from dies can have different lengths and it is therefore necessary to be able to adapt the travel of the ejector mechanism to the length of the pressing to be ejected. An ejector mechanism has been proposed in which the adaptation of the ejection stroke to the length of the pressing to be ejected is effected by changing cams on a corresponding shaft. The changing of cams however necessitates relatively long periods of idleness for the press. Moreover, it is not possible in practiceto achieve an infinitely variable control of the ejection strokes by changing cams as this would involve keeping an enormous number of different cams in stock.

An ejector mechanism has also been proposed in which the adaptation of the ejection stroke to the length of the pressing to be ejected can be carried out in an infinitely variable fashion within a specific range. In this previously proposed mechanism described in German patent specification No. 1,059,268, control railsare provided whose directions of movement are adjustable. When adjusting the ejection stroke, it is necessary in this previously proposed mechanism to carry out complex and time-consuming adjustment as, when the control tails are adjusted, both the forward point and the rearward point of the stroke are altered.

According to the present invention there is provided a die press ejector mechanism having a variable stroke length with one end of the stroke fixed, the stroke length being determined by angular movement of a first rocking lever to which motion is transmitted from a reciprocatable linear driving surface by way of an inter? mediate member which is linearly displaceable parallel to the driving surface to different chosen positions in order to vary the angular movement of the lever without altering the angular position from which such movement commences.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an ejector mechanism in a multistage press; and

FIG. 2 is a section along line II-II of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings the multistage press has several dies horizontally disposed and arranged one below the other. Press tools (not shown) are arranged opposite the dies 1 in the conventional manner and are fitted on a horizontally traversable saddle (not shown). Parts (not shown) which are to be formed are pressed into the dies with the aid of press tools. Each die is assigned an ejector 3 movable in the direction of operation of the press so as to eject the parts from the dies 1..The ejectors 3 are actuated through respective ejector bars 4 which cooperate with a slot 5 in which a lever arm 6 of a bell crank rocking lever 8 carried on a pivot 7 is engaged. As will be noted in FIG. 1, the bell crank rocking lever 8 is a first order lever, which is defined as a lever having its fulcrum pivot intermediate the ends, with the load and effort on opposite ends of the lever. A control shaft 9 drivable-in the direction of the arrow A which carries a number of cams 10 equal to the number of dies 1 is provided for actuating the ejectors 3. Each cam 10 is engaged through a roller 11 with a bell crank intermediate lever 12 mounted on a pivot 13. Intermediate lever 12 is also a first order lever.

The roller 1 1 is fitted to a first arm 14 of the intermediate lever 12. An arrangement 15 serves to ensure that the roller 11 maintains contact with the cam 10, and is articulated to the first arm 14. A second arm 16 of the intermediate lever 12 has a planar face 17. A roller 18 which is adjustably mounted on a spindle 20 attached to a first arm 19 of the rocking lever 8 bears against the face 17. The mounting is such that the roller 18 can be displaced along the first arm 19. The adjustment of the roller 18 along the length of thelever arm 19 is arranged to be at all times parallel to the planar surface 17.

When the cam 10 rotates in the direction of the arrow A, the first arm 14 of the intermediate lever 12 is pivoted towards the left of the drawing and the second arm 16 is pivoted towards the right. The first arm 19 of the lever 8 is likewise pivoted towards the right so that the second arm 6 is pivoted towards the left to actuate the ejector 3 through the slot 5.

The stroke of the ejector can be adjusted by adjusting the roller 18 with the spindle 20 on the first arm 19. The surface 17 is disposed parallel to the path of adjustment of the roller 18 and therefore the forward point of the ejector 3 remains unchanged at all times, while the length of the stroke is altered. Displacement of the roller 18 changes the effective lengths of the second and first arms 16 and 19 in relation to each other and this causes the length of the stroke of the ejector 3 to be modified.

The ejector mechanism described provides an ejection stroke which is substantially infinitely variable over its operating range and in which the forward point of the ejector piston is not modified when the length of the ejection stroke is changed. It is therefore no longer necessary when adjusting the length of the ejector stroke to readjust the forward point. This is always held at the same position irrespective of the length of the pressing being ejected. This ejector mechanism is applicable to molds.

The ejection stroke can be adjusted to an infinitely variable fashion by displacing the roller on the rocking lever, without having to exchange the associated cam, and at the same time the forward point of the ejection stroke can be maintained. The time at which the forward dead center point is reached, however, is adjustable.

We claim:

1. A die press ejector mechanism having a variable stroke length, with one end of the stroke fixed in position, said mechanism comprising:

a first lever supported for oscillatory movement about a first pivot axis; a cam engaging said lever to oscillate the same;

said first lever having a planar surface perpendicular to its plane of oscillatory movement; I

a second lever supported for oscillatory movement about a second pivot axis parallel to said first pivot axis;

said second lever having a roller adjustably supported thereon that rides on said planar surface of said first lever;

means for shifting the position of said roller toward or away from said second pivot axis along a path parallel to said planar surface, thereby changing the effective moment arm from said roller to said second pivot axis, and from said roller to said first pivot axis; and

a reciprocating ejector connected to said second lever and actuated thereby when said first lever is oscillated by said cam, said ejector being movable between a first terminal position and a second terminal position;

said first and second levers being so arranged that said planar surface is parallel to a radius passing through said second pivot axis when said ejector is in one of said terminal positions, whereby the angular position of said second lever remains the same when said ejector is in said one terminal position regardless of the distance of said roller from said second pivot axis, the length of travel of said ejector being variable according to the distance of the roller from said second pivot axis.

2. A die press ejector mechanism as in claim 1, wherein said first lever is a first-order lever.

3. A die press ejector mechanism as in claim 1, wherein said second lever is a first-order lever.

4. A die press ejector mechanism as in claim 1, wherein both said first lever and second lever are firstorder levers.

5. A die press ejector mechanism as in claim 2, wherein said cam engages one arm of said first lever, and the other arm of said first lever has said planar 'surface formed on the extremity thereof.

6. A die press ejector mechanism as in claim 4, wherein said cam engages one arm of said first lever, and the other arm of said first lever has said planar surface forrned on the extremity thereof; said second lever having one arm connected to said reciprocating ejector, and the other arm thereof has said roller adjustably supported thereon.

7. A die press ejector mechanism as in claim 6, wherein the support for said roller comprises a movable carrier for said roller and an adjusting screw extending parallel to the line of travel of said roller and having threaded engagement with said carrier. 

1. A die press ejector mechanism having a variable stroke length, with one end of the stroke fixed in position, said mechanism comprising: a first lever supported for oscillatory movement about a first pivot axis; a cam engaging said lever to oscillate the same; said first lever having a planar surface perpendicular to its plane of oscillatory movement; a second lever supported For oscillatory movement about a second pivot axis parallel to said first pivot axis; said second lever having a roller adjustably supported thereon that rides on said planar surface of said first lever; means for shifting the position of said roller toward or away from said second pivot axis along a path parallel to said planar surface, thereby changing the effective moment arm from said roller to said second pivot axis, and from said roller to said first pivot axis; and a reciprocating ejector connected to said second lever and actuated thereby when said first lever is oscillated by said cam, said ejector being movable between a first terminal position and a second terminal position; said first and second levers being so arranged that said planar surface is parallel to a radius passing through said second pivot axis when said ejector is in one of said terminal positions, whereby the angular position of said second lever remains the same when said ejector is in said one terminal position regardless of the distance of said roller from said second pivot axis, the length of travel of said ejector being variable according to the distance of the roller from said second pivot axis.
 2. A die press ejector mechanism as in claim 1, wherein said first lever is a first-order lever.
 3. A die press ejector mechanism as in claim 1, wherein said second lever is a first-order lever.
 4. A die press ejector mechanism as in claim 1, wherein both said first lever and second lever are first-order levers.
 5. A die press ejector mechanism as in claim 2, wherein said cam engages one arm of said first lever, and the other arm of said first lever has said planar surface formed on the extremity thereof.
 6. A die press ejector mechanism as in claim 4, wherein said cam engages one arm of said first lever, and the other arm of said first lever has said planar surface formed on the extremity thereof; said second lever having one arm connected to said reciprocating ejector, and the other arm thereof has said roller adjustably supported thereon.
 7. A die press ejector mechanism as in claim 6, wherein the support for said roller comprises a movable carrier for said roller and an adjusting screw extending parallel to the line of travel of said roller and having threaded engagement with said carrier. 